Gaseous electric discharge device



Dem 9 I H. ALTERTHUM ETAL 82 7 GASEOUS ELECTRIC DISCHARGE DEVICE FiledMarch 19. 1938 VOLTAGE CURRENT INVENTORS Hams Alterthum. Arveol Lompe BY6' J A;TORNEY Patented Dec. 12, 1939 Hans Alterthum, Berlin-Wilmersdorf,and Arved Lompe, Berlin, Germany, assignors to General Electric Company,a corporation New York Application March 19, 1938, Serial No. 197,029

In Germany March 30, 1937 3 Claims.

The present invention relates to gaseous electric discharge devices ofthe positive column type.

Gaseous electric discharge devices of the positive column glow dischargetype, that is a dis- 5 charge of high voltage and low amperage, are

preferably provided with cold, hollow cylindrical electrodes and haveneon therein at a pressure of about 1 to 20 mm. Such devices are usefulin the advertising field. The starting pbtential of such devices isconsiderably higher that the operating voltage thereof and a seriesresistance is required for dissipating the excess voltage during theoperation of the device. Even though the starting potential werenohigher than theopcrating voltage a series ballast would still berequired due to the negative volt-ampere characteristic of such devicesand a high voltage current supply source would still be required for thesame reason.

The object of the present invention is to propositive to negative. Whenthe percentage of argon is higher than 0.5% the visible light output-ofthe lamp is reduced so that the lamp device is less effective foradvertising purposes. When the total gas pressure is greater than 8 mm.5} the device does not have a'positive volt-ampere characteristic. Thusthe total gas pressure and the percentage of argon are critical tosuccess in the present invention.

The unexpected influence of the argon addi- 1 tions on a property ofneon tubes which hitherto was thought. to be unchangeable, cannot beexplained by any of the concepts concerning gaseous electric discharge.We have demonstrated, however, by probe measurements, that the cathode15 drop at. the hollow cylindrical electrodes, which is independent ofcurrent strength when pure vide a highly efiicient gaseous electricdischarge device of the positive column type having a gaseous atmospheretherein consisting of fixed gas and which has a positivevolt-amperecharacteristic.

We have discovered that when the total pressure of the fixed gas in agaseous electricdischarge device of the above type is from 4 to 8 mm.and when from 0.2 to 0.5% of argon is added to the neon the gaseouselectric discharge lamp device has apositive volt-ampere characteristicover a'current range of between a few niilliamperes to -the order of 50to 100 milliamperes. At higher currents the volt-ampere characteristicgradually changes from positive to negative.

Due to the presence of argon the starting potential of the device islower than when the device contains only neon and a comparatively smallseries resistance is suiiicient for dissipating the excess voltageduring the operation of the device. Since the device has a positivevoltampere characteristic no ballast resistance is required whichsimplifies the circuit and increases the .eficiency of the device byeliminating the 46 waste of energy which takes place in such resistance.

It is essential that the total gas pressure and neon is used in thedevice, increases with a rising-current strength when the gas mixture ofthe present invention is used. Probe ineasure- 20 ments also reveal thatthe volt-ampere characteristic of the positive column discharge, whichis strongly negative with pure neon, is positive with' the gas mixturesor the invention.

Devices embodying the invention are capable 25 that electro-phoresisdoes not cause a separation of the two rare gas components and thus theloss of the desirable characteristics of the device re- 30 l suitingfrom the definite relation of the gases the percentage of argon bewithin the limits specified above if the advantages of the invention 50;are to be secured. We have observed that when the percentage of argon isless than 0.2%, or when the pressure of the gaseous filling is less than4 mm. the argon is absorbed aftera comparatively short period ofoperation and the volt- .13 ampere characteristic of. the device changesfrom of the mixture. Thermionic electrodes are useful in devicesembodying the invention but due to the negative volt-amperecharacteristic of such electrodes we prefer to use one thermionic elec-35 trode which is either heated by the discharge or by a special heatercurrent.

The operating circuit of the devicesembodying the invention consists, asshown in Fig. 1, of means to supply a current of a voltage which 40 isadapted to the other ignition facilitating agents on the device and asmall resistance which dissipates the difierence between this supplyvoltage and the operating voltage of the device. Due to the presence ofargon a starting potential of about -100 volts above the operatingvoltage of the device is suflicient. With reference to Fig.

2 of the drawing, the supply-voltage and the series resistance arepreferably such that a straight line drawn through a point representing50 the voltage of the current source on the ordinate axis of a graphwhereon a curve 1) representing the relation between voltage and currentofthe lamp is plotted and a point 0 representing the operating currentand voltage of the lamp device on the rising part of said curve issteeper than a line a drawn through the point on the ordinate axisrepresenting the voltage of the current source and tangent to theaforesaid curve on the descending part thereof. (See Rudolph SeeligerPhysik der Gasentladungen 2nd edition, 1934, starting at page 128.) Achange in the volt-ampere characteristic of the device from positive tonegative is thus avoided. This undesired change from a positive to anegative volt-ampere characteristic is avoided when the voltage suppliedto the device, represented by the line a, is lower than the maximumvoltage at which the device still has a positive volt-amperecharacteristic.

In the drawing accompanying and forming part of this specification anembodiment of the invention is shown in Fig. 1 in a front elevational,partly sectional view, and

Fig. 2 is a graph showing the electrical characteristics of the circuit.

Referring to the drawing the gaseous electric discharge device comprisesan elongated, tubular container I having cold sheet iron electrodes 2and 3 sealed therein at each end thereof. Said container I has a gaseousatmosphere therein consisting of neon containing about 0.2% argon, thetotal pressure of the fixed gas being 6 mm. The container I has adiameter of 20 mm. and the electrodes 2 and 3 are separated a distanceof 1 meter. The electrodes are 50 mm. in length and 1'? mm. in diameter.The device has a resistance 4 connected in series therewith across theterminals of an alternating current source 5. Such a device operatesstably without a series series ballast when the above current andvoltage conditions are observed. 7

While we have shown and described and have pointed out in the annexedclaims certain novel features of the invention, it will be understoodthat various omissions, substitutions and changes in the forms anddetails of the device illustrated and in its use and operation may bemade by those skilled in the art without departing from the broad spiritand scope of the invention.

What we claim asnew and desire to secure by Letters Patent of the UnitedStates is:

1. In combination, a gaseous electric discharge lamp device of thepositive column type comprising a container, electrodes sealed therein,a gaseous atmosphere therein consisting of neon and .argon, the totalpressure of the gaseous filling being 4 to 8 mm., the argon being 0.2%to 0.5% of the neon and means to supply a current of from a fewmilliamperes to 100 milliamperes to said device whereby said deviceoperates stably with a positive voltage-current characteristic.

2. In combination, a gaseous electric discharge lamp device of thepositive column type comprising a container, electrodes sealed therein,a gaseous atmosphere therein consisting of neon and argon, the totalpressure of the gaseous filling being 6 mm., the argon being 0.2% of theneon and means to supply a current of from a few milliamperes to 100milliamperes to said device whereby said device operates stably with apositive voltage-current characteristic.

3. In combination, a gaseous electric discharge lamp device of thepositive. column type comprising a container, electrodes sealed therein,one of said electrodes being a cold electrode, another of saidelectrodes being a thermionic electrode, a gaseous atmosphere thereinconsisting of neon and argon, the total pressure of the gaseous fillingbeing 4 to 8 mm., the argon being 0.2% to 0.5% of the neon and means tosupply a current of from a few milliamperes to 100 milliamperes to saiddevice whereby said device operates stably with a positivevoltage-current characteristic.

HANS ALTERTHUM. ARVED L-OMPE.

